The main opposition group, the Syrian National Coalition, has long insisted that President Assad must go before any talks take place.

Mr Lavrov is due to visit London next week for talks with UK Foreign Secretary William Hague.

Both countries say the Syrian crisis will top the agenda. Russia has traditionally been a close ally of the Syrian government and is the country's biggest arms supplier.

But while there is agreement that a negotiated settlement is the best way forward, Mr Lavrov told the BBC there was no question of Russia asking President Assad to stand aside.

"I can only say it is not for us to decide who should lead Syria. It is for the Syrians to decide," he said.

Asked if there was any chance of Russia urging President Assad to stand aside, he said: "Absolutely not. You know that we are not in the regime-change game. We are against interference in domestic conflicts."

Mr Lavrov added that this was a point of principle and that, in any case, President Assad has no intention of resigning.

Asked if there was any common ground between Britain and Russia on Syria, Mr Lavrov said: "I don't think we are far apart as far as the eventual goal is concerned. We both want Syria to be united, to be democratic. We both want the Syrian people to choose freely the way they would like to run their country.

"That has been the Russian position... since the crisis started."

The conflict has caused destruction in large parts of Syria's cities, like here in Homs

Mr Lavrov said he welcomed some of the "constructive elements" in the recent position of the Syrian National Coalition.

"The leader of the coalition has been speaking about his interest in dialogue," Mr Lavrov said.

"The government reiterated its readiness to do the same including with those who are fighting on the ground. I believe we must encourage this trend on both sides."

He said he would be discussing such developments in detail with William Hague.

"Unless we all act in sync, telling the parties we don't want any military solution, that we don't want any further loss of Syrian lives, that we want them to start negotiating in earnest... this crisis will continue and more blood will be shed," he said.

The UN estimates that about 70,000 people have died since the uprising against President Assad began nearly two years ago.

The UN also says about one million Syrians have now fled abroad, and some 2.5 million have been forced from their homes inside the country.

On Thursday the medical charity Medecins Sans Frontieres said Syria's healthcare system had been wrecked by the conflict.